Tailoring magnetic mesoporous silica spheres-immobilized lipase for kinetic resolution of methyl 2-bromopropionate in a co-solvent system

摘要

We report the facile synthesis of magnetic mesoporous silica spheres (MMSS) by combining the hydrothermal method and pyrolysis process. The mesostructure, morphology and magnetization of the as-synthesized MMSS can be tailored by adjusting the mass ratio of trimethyl benzene-to-Pluronic P123 triblock copolymer (EO20PO70EO20, MW = 5800; P123) and the amount of ferric acetylacetonate. Lipase from Candida cylindracea (CCL) immobilized by the resulting MMSS with well-defined microsphere structure, uniform mesopore size (similar to 6.7 nm), large surface area (515 m(2) g(-1)) and high saturated magnetization (8.7 emu g(-1)) was employed for kinetic resolution of methyl 2-bromopropionate in aqueous buffer/organic co-solvent; as a result, excellent catalytic performance was obtained with 18% chemical yield and 96.2% enantiomeric excess (ee(S)) of methyl (S)-2-bromopropionate. Moreover, the CCL/MMSS can be easily separated from the reaction system for repetition due to high magnetization, and exhibits a superior stability (83.2% retention) even after 8 cycles in terms of yield and ee(S).